Abstract

Evidence for an entirely new stratigraphic scheme for the Vercors "Urgonian limestones " is presented. These Barremian-Bedoulian beds are subdivided into 13 units, which have been observed in the Urgonian and the neighbouring Vocontian series; numerous ammonites present in the latter allow them to be dated. For the first time in France, the following can be shawn: - at the base of the Upper Barremian, presence of a level with Matheronites orbignyanus. - at its top, existence of the securiformis Zone. The Upper Barremian biostratigraphic scheme of the Russian authors can thus be applied to the western part of the Tethys.